The overall objective is to identify and describe, at a fundamental level, the biological mechanisms relating bacterial products in plaque and gingival debris to alveolar bone resorption in periodontal disease. Primarily, a bone tissue culture model using chemically-defined media will be used. Bone resorption will be assessed quantitatively by the release or previously incorporated Ca45 from paired test and control bones from 19 day old fetal rats. We also are attempting to develop a monkey model for periodontitis using I125 absorptiometry as a highly sensitive and nondestructive technique to assess alveolar bone loss. The long-term goal is to secure information which can be used in the diagnosis, prevention and treatment of alveolar bone loss in human periodontal disease.